The objective of the parent study is to investigate possible causal mechansisms associated with an increased incidence of idiopathic pulmonary hemosiderosis in a geographic cluster area in the eastern Cleveland metropolitan area. In the process of the investigation by the Centers for Disease Control and Prevention, several lines of evidence point toward an etiological role of mycotoxins from an unusual fungus, Stachybotrys chartarum. Extensive environmental sampling of patient and control homes, done by NIOSH, found this fungus in all but one of the 12 patient homes studied and in 16 of 29 control subject homes. Two manuscripts are being submitted. The purpose of this addendum involving the GCRC is to further investigate control subjects who are at-risk for pulmonary hemosiderosis due to Stachybotrys in their homes. Follow-up visits of all affected infants continue.